The invention relates to minimally invasive surgical instruments.
Minimally invasive surgical techniques, including endoscopic (gastrointestinal) and laparoscopic (abdominal) procedures, employ surgical instruments that are inserted into the body through a pre-existing orifice or a small puncture or incision rather than the larger incision used in traditional, "open" surgery. Minimally invasive procedures have several advantages over open surgery, the main one being minimization of trauma to healthy tissue. As a result, recovery is accelerated and the risk of complications from infection and scar adhesion is reduced. These considerations have motivated the application of minimally invasive techniques wherever feasible. However, the instruments used in these minimally invasive procedures impair or reduce surgical access, dexterity, efficiency, and in some cases safety, when compared to the use of standard instruments in open surgery.
Nearly all minimally invasive procedures employ means for imaging the surgical site in real time. These may be non-invasive, e.g., fluoroscopy, or invasive, using, for example, an optical fiberscope. Such "scopes" can be flexible, like the endoscope, which is employed in the gastrointestinal tract, or, when the operative site is sufficiently accessible, rigid, like the laparoscope, which is used in abdominal surgery. In both endoscopy and laparoscopy, viewing light is delivered to the surgical site by fiber optics, and the surgeon views the site on an external CRT.
Laparoscopic surgery takes place in an approximately 20.times.20.times.20 cm workspace inside the patient created by insufflating the abdominal cavity with air or a gas such as carbon dioxide. The laparoscope and laparoscopic instruments are inserted into the body through a 5 to 12 mm diameter cannulae inserted through one or more puncture incisions in the abdominal wall. There are many instruments available for use in laparoscopic procedures including biopsy forceps, various types of graspers, scissors, electrocautery devices, staplers, clip appliers, needle holders, and suture loops for ligation.
In spite of the benefits, there are several limitations of the laparoscopic instruments that make laparoscopy more awkward for the surgeon than traditional, open surgery, and the nature of the instruments require a long learning curve for a surgeon to become proficient in their use. Even after learning how to use these instruments properly, surgeons still lack a certain amount of dexterity, which makes some tasks, such as suturing and knot-tying inside the body cavity, difficult.
Based on the known disadvantages, attempts have been made to improve the position, tactile, and force senses perceived by the surgeon using these laparoscopic instruments in minimally invasive procedures. Force feedback assists in suture and knot tensioning and protects against inadvertent laceration of tissue outside of the field of view of the scope. Tactile sensing is useful for manipulating suture material or other objects held with the instruments, localizing small anatomical features such as subsurface blood vessels, and detecting features that are obscured from the video camera.
Efforts at implementing tactile feedback with these instruments have focused on elaborate linkage designs or the use of complex strain sensor arrays on the tip of the instrument coupled to stimulator arrays worn on the surgeon's fingertips, e.g., on a glove, at a point remote from the tip of the instrument. Such systems have had some experimental success, but are complicated, both to design and to manufacture.